Systems for Folding Doors
Introduction
A folding door, also known as a bi-fold or accordion door, is an architectural element consisting of multiple hinged panels that fold and stack against one another when opened, often guided by a track along the floor or ceiling to facilitate smooth movement and maximize space efficiency.[1] These doors are designed to create versatile partitions or openings, allowing for seamless transitions between spaces while providing options for privacy and airflow.[2]
Folding doors trace their origins to ancient civilizations, with evidence of accordion-style mechanisms used by the Romans in architectural projects as early as the 1st century CE, as seen in excavations at Pompeii where they served functional and decorative purposes in public and private structures.[3] Over time, their design evolved through medieval and Renaissance periods, incorporating wood and metal frames, before modern iterations emerged in the mid-20th century with patents for lightweight, track-based systems that enhanced durability and ease of use.[4] Today, they are widely employed in residential, commercial, and institutional settings for interior room dividers, exterior patio enclosures, and flexible office partitions, prized for their ability to blur boundaries between indoor and outdoor environments.[5]
Common types include bi-fold doors, which feature an even number of panels folding in pairs for compact stacking; multi-fold doors, allowing uneven panel configurations for wider openings; and accordion doors, which zigzag in a continuous pleated manner for maximum flexibility.[6] Materials vary by application, with aluminum frames offering slim profiles, weather resistance, and low maintenance for exterior uses, while wood provides a warm aesthetic for interiors, and uPVC or composite options balance cost and insulation.[7] Often glazed with tempered glass, these doors enhance natural light and views, contributing to energy-efficient, open-plan designs in contemporary architecture.[8]
History
Ancient origins
The earliest documented references to folding doors appear in biblical accounts of Solomon's Temple in Jerusalem, constructed around the 10th century BCE. According to 1 Kings 6:34, the temple featured two doors made of cypress wood, each consisting of two folding leaves that turned on pivots, allowing them to open inward or fold against the walls for access to the inner sanctuary.[9] These massive panels, overlaid with carvings of cherubim, palm trees, and open flowers, and further embellished with gold, served as grand entrances emphasizing both functionality and symbolic grandeur in religious architecture.[9]